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排序方式: 共有63条查询结果,搜索用时 15 毫秒
1.
Testing an earthquake prediction algorithm 总被引:1,自引:0,他引:1
Vladimir G. Kossobokov John H. Healy James W. Dewey 《Pure and Applied Geophysics》1997,149(1):219-232
A test to evaluate earthquake prediction algorithms is being applied to a Russian algorithm known asM8 TheM8 algorithm makes intermediate term predictions for earthquakes to occur in a large circle, based on integral counts of transient seismicity in the circle. In a retroactive prediction for the period January 1, 1985 to July 1, 1991 the algorithm as configured for the forward test would have predicted eight of ten strong earthquakes in the test area. A null hypothesis, based on random assignment of predictions, predicts eight earthquakes in 2.87% of the trials. The forward test began July 1, 1991 and will run through December 31, 1997. As of July 1, 1995, the algorithm had forward predicted five out of nine earthquakes in the test area, which success ratio would have been achieved in 53% of random trials with the null hypothesis. 相似文献
2.
Weathered granite extends 70 m deep at Hi Vista in the arid central Mojave Desert of southern California. The low strength of this granite is due to the alteration of biotite and chlorite montmorillonite. Deep weathering probably occurs in most granites, although we cannot rule out some anomalous mechanisms at Hi Vista. Geophysical instruments set in these slightly altered rocks are limited by the unstable behavior of the rocks. Thus, tectonic signals from instruments placed in shallow boreholes give vague results. Geophysical measurements of these weathered rocks resemble measurements of granitic rocks near major faults. The rheology of the rocks in which instruments are placed limits the useful sensitivity of the instruments. 相似文献
3.
Tropical cooling and the isotopic composition of precipitation in general circulation model simulations of the ice age climate 总被引:2,自引:0,他引:2
We test the climate effects of changes in the tropical ocean by imposing three different patterns of tropical SSTs in ice
age general circulation model simulations that include water source tracers and water isotope tracers. The continental air
temperature and hydrological cycle response in these simulations is substantial and should be directly comparable to the paleoclimatic
record. With tropical cooling imposed, there is a strong temperature response in mid- to high-latitudes resulting from changes
in sea ice and disturbance of the planetary waves; the results suggest that tropical/subtropical ocean cooling leads to significant
dynamical and radiative feedbacks that might amplify ice age cycles. The isotopes in precipitation generally follow the temperature
response at higher latitudes, but regional δ18O/air temperature scaling factors differ greatly among the experiments. In low-latitudes, continental surface temperatures
decrease congruently with the adjacent SSTs in the cooling experiments. Assuming CLIMAP SSTs, 18O/16O ratios in low-latitude precipitation show no change from modern values. However, the experiments with additional cooling
of SSTs produce much lower tropical continental δ18O values, and these low values result primarily from an enhanced recycling of continental moisture (as marine evaporation
is reduced). The water isotopes are especially sensitive to continental aridity, suggesting that they represent an effective
tracer of the extent of tropical cooling and drying. Only one of the tropical cooling simulations produces generalized low-latitude
aridity. These results demonstrate that the geographic pattern of cooling is most critical for promoting much drier continents,
and they underscore the need for accurate reconstructions of SST gradients in the ice age ocean.
Received: 26 July 1999 / Accepted: 10 July 2000 相似文献
4.
5.
On the basis of the newest interpretations of all sufficiently long seismic profiles, a contour map of the Mohorovi?i? discontinuity for the conterminous United States is compiled. Differences from earlier interpretations are discussed. 相似文献
6.
During the activation of zinc sulphide with the heavy metal ions CuII, CdII and PbII, metal-ion uptake follows a logarithmic dependence on time. A reaction mechanism is proposed which is consistent with experimental observations. Incident radiation has a strong influence on the activation reaction, an effect which is interpreted in terms of semiconductor theory. 相似文献
7.
A new mass-spectrometric technique, capable of the quantitative detection of very low levels of elemental sulphur on sulphide mineral surfaces has been developed. It is shown that elemental sulphur is formed, under certain conditions, on zinc sulphide surfaces activated by CuII, CdII and PbII. The findings are interpreted in terms of semiconductor theory. 相似文献
8.
9.
In the three decades since their discovery, the accumulated body of observational data from pulsar sources puts constraints on models that seek to explain their periodic radiation. This paper reviews this data, reports on a VLA search for haloes predicted by an early model, and reinvestigates a magnetospheric disk-field-aligned-current transmission line system as the origin of the observed radiation, with external wave excitation by as yet an unexplained source. Three dimensional, fully electromagnetic particle-in-cell simulations of the pulsar surface and magnetosphere are used to explore the waveshape and polarization properties of the observed radiation. 相似文献
10.
Dao HV Ngeh LN Bigger SW Orbell JD Healy M Jessop R Dann P 《Marine pollution bulletin》2006,52(12):1591-1594
Iron powder has previously been demonstrated to be effective in the removal, via magnetic harvesting, of a wide variety of oil contaminants from feathers and plumage. This study investigates the efficacy of magnetic cleansing for the removal from feathers of tarry contamination that has been allowed to weather. Clusters of feathers from Mallard duck (Anas platyrhnchos) and Little Penguin (Eudyptula minor) were completely immersed in a tarry contaminant and allowed to weather from one to fourteen days. The contaminant was removed using a magnetic cleansing protocol and the removal efficacy assessed gravimetrically. For one, seven and fourteen days of weathering, a final removal (after fourteen treatments) of more than 99% and 97% was achieved for duck feathers and penguin feathers, respectively. Repeating the experiments (for a seven-day weathering period) for both duck and penguin feathers, with the judicious application of a pre-conditioner (olive oil), further improved removal efficacy. A convenient method to screen for improved pre-conditioning agents is suggested. 相似文献